Oxidized galectin-1 inhibits LPS activity to increase cytokines in macrophages

Objectives: Periodontitis is prevalent in aged humans. Limiting inflammation associated with periodontitis may provide a therapy for this condition, since gram-negative bacteria – which express lipopolysaccharide (LPS) – have a key role in its initiation. Since oxidized galectin-1 (GAL-1/Ox) regulates the inflammatory response in other systems, we sought to establish whether this galectin-1 mRNA is expressed in the oral cavity, and whether it could dampen LPS-induced macrophage activation in vitro. Methods: Using RT-PCR, we measured galectin-1 mRNA expression to clarify its localization to rat gingival tissues and studied the effect of P. gingivalis challenge on galectin-1 expression. Next, we tested the effects of adding GAL-1/Ox to cultured LPS-activated peritoneal macrophages on mRNA expressions of pro-inflammatory factors by RT-PCR. Result: We established that galectin-1 mRNA is expressed in gingival tissues and also showed that galectin-1 mRNA significantly increased by the challenge with P. gingivalis indicating galectin-1 may regulate oral inflammation. On the other hand, LPS (100 ng/ml) induced macrophages to upregulate mRNAs associated with a pro-inflammatory response: IL-1beta, IL-6, and iNOS. We show that GAL-1/Ox application (10 ng/ml) to LPS-treated macrophages reduced the LPS-induced increase in pro-inflammatory mRNA expression. Conclusion: GAL-1/Ox restricts the pro-inflammatory actions of LPS, and this protein could limit the negative effects of inflammation in periodontitis.